Yep I am going to nix the BBB on the tub. Tested tonight and the CL was 0. I was at 10.6 yesterday at the same time. The tub hasn't been used in three days so it cannot be anything that we are putting in that's killing the CL. It just disappears so fast in such a small tub, I guess. Don't see any choice but to drain tomorrow and re-baquacize it.